DESCRIPTION (Adapted from the investigator's application): Understanding the dynamics of biological molecules is a major goal of contemporary biology and progress has been in the direction of analysis of single molecules utilizing patch clamp recording, laser traps and atomic force microscopy. The study of single molecules provides the opportunity to directly measure molecular rate constants as well as the output properties such as current, displacement or force. Combined with the ability to readily alter molecular structure using site directed mutagenesis, the analysis of molecular kinetics provides unparalleled insights into molecular structure and function that are difficult to obtain by other methods. The analysis of currents from single channels has the most extensive history of single molecule kinetic techniques. While there are about 5,000 papers per year appearing on ion channels, almost none utilize the vast array of kinetic information contained in the data. Most deal with average properties such as the probability of being open or the mean current. A major reason for the lack of detailed analyses is the difficulty of solving the inverse problem -- going from data to the model. Most biologists do not posses the requisite mathematical skills and those with the skills rarely attempt such analyses because of the time required, the difficulty of checking the results against alternative models and the difficulty of establishing error limits. the goal of this proposal is to extend current algorithms and to develop user friendly software that can serve as a "kinetics calculator" for stochastic molecular data; software that can quickly and easily solve the inverse problem (to the extent that such problems are invertible). The software will not require the user to be mathematically adept or knowledgeable about algorithms. The current software runs in UNIX environment utilizing both command line and Motif graphical interfaces. A variety of algorithms provide optimization and segmentation. This software will be unified and extended using improved and ported to the more common IBM/PC and perhaps MacIntosh environments. Success of this project is expected to lead to establishment of a national user facility supporting the analysis of stochastic molecular kinetics.